This invention relates to a container handling system for a vehicle, and more specifically, to a container handling system commonly known as a xe2x80x9chook liftxe2x80x9d.
So-called xe2x80x9chook liftsxe2x80x9d on trucks have been extensively employed for the transport of various materials in a container. In the usual case, the container may be loaded or unloaded upon the bed of the truck utilizing the hook lift system. One typical and frequent use for such systems is in the picking up and hauling of refuse. An open ended container may be delivered to a point of use and the hook lift used to deploy the container on the terrain underlying the truck where it is left to be filled with refuse or the like. When the container is full, the truck returns to the point where the container has been deposited and through use of the hook lift system, elevates the now full container onto the truck where it may be transported, along with its contents, to a point where the contents are deposited.
U.S. Pat. No. 3,892,323 issued Jul. 1, 1975 to Corompt discloses a particularly useful version of that system. A jib with an upright hook to engage the container is slidably mounted in a tube or the like for extension or retraction with respect thereto. The tube, oppositely of the jib, is connected to a frame element by a pivot which in turn is pivoted to the main frame or bed of the truck by another pivot located rearwardly of the first. A hydraulic cylinder is connected to the tube and a latching system is employed whereby when the jib is retracted, the tube and the pivotal frame move as a unitary part to allow the container to be dumped while still mounted on the track by elevating the frame with a hydraulic cylinder. On the other hand, when the jib is extended with respect to the tube, the tube is unlatched from the frame allowing the tube and jib only to be pivoted about the first mentioned pivot for loading or unloading the container from the vehicle. Thus, the system may be operated in a container loading mode, a container transporting mode, a container unloading mode, or a container dumping mode.
In spite of these advantages, the system of Corompt is not as useful as might be. Torsional loadings placed on the lift system as a result of uneven loading within the container from side to side or other forces imposed upon the jib when connected to the container can cause damage to the system.
Container handling systems of the type disclosed such as that of the above-identified Corompt patent also require some sort of a latch for latching the tube to the dump frame thereby disabling or rigidifying the pivotal connection between the two. This latch must be selectively operable and typically will be such that the two will be unlatched, and therefore able to pivot relative to one another, when the system is operating in the loading or unloading modes. On the other hand, when the system is operating in the transport or dumping modes, the latch should be engaged.
A latching system such as that shown by Corompt, therefore, is disabled when the jib is fully retracted with respect to the secondary frame. Systems heretofore designed typically include one or more pivots and return springs for a latch lever. In the environment in which such systems operate, the pivots may resist free movement of the latch lever as a result of corrosion, the intrusion of environmental materials, or the like and not operate satisfactorily to provide the desired latching or unlatching. Moreover, the use of pivots and springs adds to the complexity of the latching mechanism, thereby adding expense and making it more prone to failure.
The present invention is directed to a system having the advantages of that disclosed in Corompt, namely, operation in the four different modes mentioned previously and which provides a high measure of resistance to torsional loading so as to minimize or eliminate the possibility of damage to the system from such torsional loading and which may include an improved latching system.
It is the principal object of the invention to provide a new and improved container handling system for use with vehicles. More specifically, it is an object of the invention to provide such a system wherein torsional loading is greatly resisted by the system so as to avoid damage thereto and/or an improved latching system.
It is also an object of the invention to provide such a system that is operable in at least four modes, namely, a container loading mode, a container transporting mode, a container unloading mode and a container dumping mode.
An exemplary embodiment of the invention achieves the foregoing objects in a system that includes an elongated main frame adapted to be mounted on a vehicle and having spaced, generally parallel side rails, a front end and a rear end. Container engaging rollers are mounted for rotation at the rear end and a first pivot is located adjacent the rollers to define a first horizontal pivot axis extending between the side rails in a direction normal thereto. A dump frame is located between the side rails near the rear end and pivoted thereto by the first pivot to pivot about the first pivot axis. A secondary frame is located between the side rails and between the dump frame and the front end. The secondary frame includes two spaced, parallel, tubular or partially tubular members and a second pivot defining a second horizontal pivot axis parallel to the first pivot axis and pivoting the second frame to the dump frame at a location spaced from the first pivot axis in the direction of the front end. A sliding jib is provided and includes two spaced, parallel tubular or partially tubular members that are telescopically received in the tubular or partially tubular members of the secondary frame to be slidable with respect thereto. A hook element interconnects the tubular or partially tubular members of the sliding jib and extends upwardly therefrom to terminate in a hook located well above a plane defined by the tubular or partially tubular members of the sliding jib. First and second fluid cylinders are disposed within respective ones of said tubular or partially tubular members of the secondary frame and connected to respective ones of the tubular or partially tubular members of the sliding jib. The first and second cylinders are operable to extend or retract the sliding jib with respect to the secondary frame. At least one third fluid cylinder is connected to the main frame near the front end thereof and to the secondary frame and is operable to pivot the secondary frame about the second pivot axis and/or the dump frame about the first pivot axis. As a consequence, the hook may be moved to engage a container on terrain underlying the main frame for loading or unloading modes, moved to a position overlying a vehicle to which the main frame is mounted so as to dispose the container in a transporting mode, or to cause the dump frame and the secondary frame to move about the first axis in a unitary fashion to operate in a dumping mode.
By reason of the fact that the jib is made of two spaced tubular members, a high degree of rigidity is imparted thereto sufficient to highly resist torsional forces applied to the jib and the secondary frame and dump frame so as to minimize or eliminate the possibility of damage to the container handling system.
It is also an object of the invention to provide a new and improved latch for rigidifying the pivot between the dump frame and the secondary frame. According to one embodiment of the invention, such a latch includes a first latch element movable with the jib and a second latch element carried by the dump frame in position to be engaged by the first latch element for the purpose of rigidifying the second pivot except when the jib is fully retracted. Preferably, the first latch element includes a relatively short tab carried by the jib and directed toward the dump frame and the second latch includes a relatively long tab overlying the short tab in interference relation. The length of the relatively long tab is such as to stop short of overlying the relatively short tab when the jib is fully retracted.
In a highly preferred embodiment, the tube member in which the jib is telescopically received has an elongated slot facing the dump frame and the relatively short tab is located to extend through the slot toward the dump frame to underlie the tab thereon.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.